Now the discussion of the new version of GMP is getting deeper and deeper, and Hujing understands the requirements and regulations of the new version

1.
Background introduction With the deepening of the new version of GMP and the continuous improvement of regulatory requirements, the negative pressure weighing cover as a weighing protection device has been widely used in the sampling room of pharmaceutical companies and the weighing and ingredient room in the workshop
.

During the weighing process in the negative pressure weighing hood, the product is often exposed, so it should naturally belong to the direct influence system that directly affects the quality of the product, and it must be verified and performance confirmed according to the principle of risk control
.

Next, we discuss some of the concerns of negative pressure weighing hood performance verification
.

2.
Test content The test of the negative pressure weighing hood should usually pay attention to parameters such as efficient on-site leak detection, airflow pattern, wind speed and uniformity, ratio of exhaust air volume, illumination, temperature, noise, cleanliness and so on
.

2.
1, Efficient leak detection If the leak detection is not carried out after the efficient installation, the installation effect and whether the efficiency will be damaged during transportation cannot be guaranteed.
Therefore, after the installation is completed, the installed efficiency will generally be installed
.

Tests use a calibrated photometer and aerosol generator, typically cold-fuming aerosol generators for devices such as weighing hoods
.

After the concentration of the aerosol generated in the upstream is stabilized between 20-30ug/L, the concentration is recorded, and then start to scan the downstream of the filter.
The scanning speed is 3-5cm/s, and the distance from the filter surface is 2-4cm.
The scanning route All filter faces and border areas should be covered, making sure to scan every area
.

 　　Judgment standard: no leakage rate of more than 0.
01% is detected in the high-efficiency downstream
.

 　　2.
2, Air flow pattern In the air flow pattern test, the product exposure position, the operator's workstation, and the flow direction of the air flow from clean to dirty should be considered comprehensively
.

Ensure that the product is exposed to uncontaminated "first-hand clean air", ensuring that there is no airflow eddy, backflow or diffusion into the operator's breathing zone to cause injury to the operator
.

The test uses a water mist generator dedicated to the airflow pattern test, and the airflow pattern is recorded with a video camera
.

 　　Judgment criteria: The airflow is in a unidirectional flow state, and there is no eddy current, reflux or diffusion
.

 　　2.
3.
Wind speed and uniformity The protective effect of the negative pressure weighing hood is formed by a good airflow at a certain wind speed.
Only uniform supply and return air can form a good airflow, and only a certain wind speed can achieve the effect of curbing the spread of dust
.

 　　A.
Supply air Use a calibrated anemometer to measure at 5-15cm directly below the air outlet surface and take a test point on each flow equalizing membrane panel
.

Take 5 points on each membrane surface, and calculate the average value and air volume
.

 　　Judgment standard: the air supply wind speed is 0.
36-0.
54m/s, and the average speed of each membrane surface is also within 10% error of the total average speed
.

In addition, no point deviates from 12% of the mean value of the film surface to which it belongs
.

 　　B, Return Air Use a calibrated anemometer to measure the return air velocity at a distance of 3-5cm from the return air grille
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Take 5 points for each return grille and calculate the average value
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 　　Judgment standard: The average speed of each part is within 10% error range of the total average, and none of the data exceeds 12% of the average wind speed of the grid where it is located
.

 　　2.
4.
The reason why the negative pressure weighing hood forms a negative pressure is that the air supply on the air supply side is smaller than the return air volume on the return air side due to the efficient exhaust air volume at the top of the weighing hood, so that the equipment must be operated from its location.
A part of the indoor air is absorbed to make up for the difference between the two to form a negative pressure area
.

The proportional control of the exhaust air volume directly determines the effect of negative pressure protection
.

 　　Use the air volume hood to measure the exhaust air volume, record the data, and then calculate the ratio between the two based on the air supply air volume obtained from the wind speed and uniformity test
.

 　　Judgment standard: The exhaust air volume should be between 5% and 15% of the total air supply volume
.

 　　2.
5, Temperature Because there is a fan in the weighing hood that generates heat during operation, if there is no cooling measures, long-term operation will cause the indoor temperature to rise to an unsuitable value
.

Generally, cooling coils can be used for weighing hoods that need to run for a long time.
For weighing hoods that do not run for a long time, the longest continuous use time can be specified to ensure that the temperature does not exceed the standard.
The solution is to cool the room separately
.

There should be exhaust air, and the weighing hood is an open device.
If the temperature rises, it will affect the entire temperature rise in the operating room where it is located
.

 　　The sampling points are distributed according to the area, not less than 0.
5 meters away from the wall, and 5 points are evenly distributed (at least one point should be ensured inside the weighing hood), and measured at the height of the working surface
.

The room temperature was recorded using a calibrated thermometer before the weighing hood was opened and the average was calculated
.

Then turn on the equipment for operation, measure the indoor temperature again before the end of the work, that is, at the longest running time, and calculate the average value
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 　　Judgment standard: The operation of the negative pressure weighing hood does not cause the indoor temperature to rise by more than 2 °C
.

 　　2.
6, Noise/Illuminance Because there are operators operating in the operating room, a certain level of noise and illumination is conducive to the comfort of the staff, thereby reducing the probability of errors
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From an EHS perspective, noise is also an indicator that should be controlled
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 　　Judgment standard: Noise: 75dB or negotiation by both parties; Illumination: 500lx or negotiation by both parties
.

 　　2.
7, Cleanliness The negative pressure weighing hood is similar to the air supply in C+A in GMP to a certain extent, and its cleanliness must meet the requirements under static conditions
.

During the measurement, the required sampling points are calculated according to the area of ​​the air outlet
.

The sampling points are evenly arranged at 0.
8 meters above the ground for testing
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 　　Judgment standard: meet the static requirements
.

 　　3.
Precautions and suggestions In addition to the above performance, the control of microorganisms is also very important, but because the control of microorganisms depends more on the management level of the entire software and hardware of the enterprise air conditioner and clean room, rather than just the negative pressure weighing hood itself , so this item is usually carried out when the performance of the air conditioner and clean room is confirmed, and is not expanded here
.

 　　During the operation, when the operation speed is increased and the operator's operation method is questionable, the exposure level is likely to increase, and may increase by an order of magnitude, depending on the characteristics of the material being handled and the actual situation
.

Practice has proved that following the following suggestions will help to exert the performance of the equipment: A.
Combined with some auxiliary tools, such as double-layer inner bags, combined with ventilation rings and ergonomic carrying tools, the performance of the equipment can be significantly enhanced
.

 　　B, Even without additional engineering controls, good operating skills and strict adherence to procedures can significantly increase equipment performance
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 　　C, A well-trained and careful operator, coupled with strict adherence to operating procedures, can produce similar and repeatable results
.